It was demonstrated by Geschwind and Levitsky (1968) that large left-right asymmetries exist in the cerebral cortex of adult human brains in areas which are probably involved in language functions. These results have been confirmed in hunam infants and fetuses, and in primitive man and non-human primates. This research proposes to study the brain for cytoarchitectonic asymmetries in Nissl preparations in the areas which show gross right-left differences. Furthermore the project will establish pigment architectonic methods in order to study microscopic asymmetries more effectively and quickly. Animal models will be sought, and application of asymmetry data to clinical radiological methods will be explored.